Sources
The course words, meanings and example sentences were written for Fahrplan Deutsch. The article pages use that list.
Ending statistics come from german-nouns, compiled from German Wiktionary, under CC BY-SA 4.0. Frequency bands come from FrequencyWords (OpenSubtitles), also CC BY-SA 4.0. The dictionary footer repeats this.
Schreib-Check can send a text to LanguageTool (LGPL-2.1). The Leben in Deutschland questions on the citizenship page follow the terms recorded in the credits: text only, wording unchanged, not an official BAMF product.
The full table, including fonts and icons, is in the repository file content/CREDITS.md and on the credits screen.